This invention relates to a pattern recognizing device, and in particular to a pattern recognizing device according to the line segment method suitable for a device for recognizing letters or patterns written by hand.
For example JP-A-60-136896 can be referred to as a publication disclosing conventional pattern recognizing devices.
According to prior art techniques, an inputted stroke of a pattern written by hand on a tablette is represented by a series of coordinate points by reading-in a coordinate point for every unit time. A segment of line is set for every time the area of a region enclosed by successively a curve formed by connecting these coordinate points and a straight line, connecting a certain coordinate point serving as the origin with an arbitrary coordinate point succeeding it, exceeds a predetermined value, so as to obtain broken line approximation data for a read-in pattern. Then it is judged whether two segments adjacent to each other are connected with an arc or they are two segments of line butted against each other with a certain angle. According to the result of this judgement the segments of line are treated as an element which is an arc when they are judged as an arc and as two elements of a broken line when they are judged as two segments of line butted against each other. In this way the read-in pattern is transformed into a series of elements, each of which is an arc or a segment of line. The pattern recognition can be effected by reading out a registered pattern which matches well, while comparing the data represented by this series of elements with a plurality of registered patterns previously defined.
However, according to these prior art techniques, it happens that characteristic values of arcs or broken lines depart from a region set for the judgement of whether the elements constitute an arc or a broken line. As a result there is a problem that the read-in pattern is transformed into erroneous data represented by a series of elements, which makes it impossible to correctly match the data with any of the registered patterns. This leads to erroneous pattern recognition.